New map type based on array map for debugging purpose

It checks multiple allocation and deallocation of map values and
some consistency.

todo:
clarification of debugging concepts
assertions - exceptions - debug
revision of attic/debug.h

motto:
testing is at least so important as coding

 /*!

 \page ugraphs Undirected graph structures

 The primary data structures of LEMON are the graph classes.

 Under construction.

 */